Means for shutting off fuel flow in the idle system of carburetors



N. c. THUESEN ET AL v MEANS FOR SHUTTING OFF FUEL FLOW IN March 24. 1970 3,502,307

THE IDLE SYSTEM oF cARBUREToRs Filed July 5. 1968 United States lPatent O 3,502,307 MEANS FOR SHUTTING OFF FUEL FLOW IN THE IDLE SYSTEM F CARBURETORS i Niel C. Thuesen, 6021 S. Compton Ave., Los Angeles, Calif. 90001, and Ralph N. Thuesen, 926 Riverside Ave., Newport Beach, Calif. 92660 Filed July 3, 1968, Ser. No. 742,215 Int. Cl. F02m 1 9/ 02 U.S. Cl. 261-52 5 Claims ABSTRACT OF THE DISCLOSURE In a carburetor, means automatically operable upon deceleration of the speed of an internal combustion engine to shut Ioli? flow of fuel in 'the idle system, and means, `sensitive to the speed of .the engine, to restore normal idling operation thereof at the end of the period `of deceleration.

BACKGROUND OF THE INVENTION Representative modern internal combustion engine-s have two operation phases-one when idling (without load) and the Iother While under throttle (usually with load). In such engines, the intake manifold, under idling conditions, is under vacuum on the order of 21" of mercury. Therefore, the idle `syste-m of carburetors is metered and adjusted to deliver proper amounts of fuel for correct idling speed for such or lower vacuums. However, during deceleration of Ian engine from normal opera-tion, the engine speed is above the idling speed and the vacuum in the intake manifold may well be on the order of 25" of mercury., As a consequence, more than the normal idling fuel is drawn through the idle system. Such additional fuel is needless, wasteful and ineiliciently burned and, therefore, contributive to air pollution. Moreover, the same contributes to fouling of the idle portion of the carburetor and, consequently, to lowering of operative efficiency.

SUMMARY OF THE INVENTION In order to carry out -the purposes of this invention, it is the object of the invention to provide -means to automatically shut off full ilow in the idle `system as the engine is decelera-ting and provide means sensitive to such deceleration to automatically restore Afuel flow to the carburetor when the vacuum in the idle phase returns to a normal idling condition.

This invention also has for its objects to provide such means that are positive in operation, convenient in use, easily installed in a working position and easily disconnected therefrom, economical of manufacture, relatively simple, and of general superiority and ser-viceability.

The invention also comprises novel details of construction and novel combinations and arrangements of parts, which will more fully appear in the course of the following description and which is based on the accompanying drawing. However, said drawing merely shows, and the following description merely describes, one embodiment of the present invention, which is given by way of illustration `or example only.

BRIEF DESCRIPTION OF THE DRAWING The figure is a semi-schematic lvie-w of a carburetor embodying the means of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT The figure shows an intake manifold 5 mounting a carburetor 6. For the purposes of this invention, the carburetor is shown only as having a float system 7, idle and olf-idle fuel `systems 8, and a throttle chamber 9 with a conventional throttle or buttery valve 10 which, in this 3,502,307 Patented Mar. 24, 1970 ICC case, has a bleed or bypass fit in said chamber. All other conventional operating systems are omitted for clarity and form no partof the present invention.

The oat system 7 is shown as housed in a bowl 11 in which is mounted a float '12 Athat controls a needle valve 13. The idle and off-idle fuel Isystems 8 are shown as an idle air bleed port 14 in the bowl 11, an idle and off-idle fuel jet 1S, and off-idle ports 16 on the inlet side of the valve 10, the ports 16, the bleed port 14, and fuel jet -15 -being connected by a passage 17, and an adjustable needle valve `18 controlling a feed port 19 connecting the throttle chamber 9, on the outlet side of said valve 10, to the passage 17.

In order that the following description of the present improvements and their functioning may be more clearly understood, the lower portion 20 of the bowl 11, below the float is shown as fllled with fuel, 'as is the conduit 21 from the fuel pump, and the passage 22 from said conduit -to the inlet of the needle valve 13, which is maintained closed by the buoyancy of the float 12 due to the fuel therebelow. During deceleration, the intake manifold 5, throttle chamber -9, passage 17, and the area 23 in the bowl 11 above the float, are occupied by the atmos- -phere at intake manifold pressure. This pressure is also manifest in a conduit system 24 -leading from the manifold 5, the purpose of which will be explained hereinafter. It will be noted that the conventional air -bleed `14 communicates the off-idle passage 17 and the bowl area 23; the conventional fuel jet 15 is submerged in the lower fueloccupied portion 20 of the bowl 11; Iand the throttle chamber 9 is connected to said passage y17 by ports 16 just above the butterfly valve 10.

The present novel improvements comprise, generally, a deceleration buttery valve assembly 25 located in the throttle chamber 9 in spaced relation above and -on the inlet side of the valve 10, and means 26 `for controlling the valve .assembly 25, the latter means being connected to `the condui-t system 24 for actuation by air in -said system in a direction to close the valve assembly 25, a return spring 27 -being provided for opening said valve assembly upon lowering of air pressure inthe conduit system.

The valve assembly 25 is here shown as an extension 28 of the throttle chamber 9 and which may comprise an integral part of said chamber or, as shown, an added tubular extension. A butterfly valve 29 is pivotally mounted on -said extension 28 and is provided with an operating arm B0.

The control means 26 is shown as a cylinder 31 connected at one end to a conduit 32 that is part of the system 24 and vented at the other end, a piston 33 in said cylinder is `subject to vacuu-m in 4said conduit 32, a stem 34 on said piston extending in the direction opposite to the direction of application of the vacuum, and a link 35 connecting said stem and the buttery arm 30. The men tioned spring 27 providing a bias opposing the movement of the piston 33 under vacuum. This exemplary means is devised for moving the valve 29 to closed position, yas shown, under vacuum and restoring the lsan-ie to open position under bias of spring 27 when the vacuum is lowered below a pre-determined level. When the valve 29 is in closed position, as shown, the pressure in the manifold 5, throttle chamber 9, and bowl area 23 quickly equalizes, thereby removing the differential in pressures that are required to cause flow of `fuel from the bowl through the olf-idle fuel system to the throttle chamber. A vent 23a from the bowl larea 23 into the upper. portion of the throttle chamber 9 is of a size to enable such quick pressure equalization.

The present means is provided with a shut-off device 36 between the inlet conduit 21 from the pump and the conduit 22 leading to the inlet to the needle valve 13. While shown as a separate unit for clarity of illustration,

this device 36 may be incorporated in the carburetor as a component thereof. The same is shown as a valve body 37 having a valve seat 38 where the conduits 21 and 22 meet, a needle valve stem 39 for controlling fuel flow past said seat and provided with a piston 40 that is subject to vacuum in a branch conduit 41 from the conduit 32, which is effective to bias the needle valve 39 to shut-off position toward its seat 38, stopping fuel flow to the bowl 11. Said valve 39 may be opened by fuel under pressure in the conduit 21 or a by spring (not shown) which has a bias counter to the bias on the valve stem by vacuum in the conduit 41.

The valve device 36 serves to prevent fiooding of the carburetor when there is a too great pressure differential across the needle valve 13, a differential that results from a lowering of the pressure in the area 23 of the bowl 11 during deceleration, as above indicated.

The vacuum conduit system 24 is shown as controlled by a solenoid valve 42, operation thereof being affected by a speed sensing switch 43 which closes when engine speed rises significantly above idling speed, and by a throttle stop switch 44 which closes when the throttle is closed. An electrical system 45 connects the solenoid 46 of switch 42 with said switches 43 and 44, the same including a current source 47 and in circuit with the ignition switch 48 of the engne which is served by the carburetor 6.

The valve 42 is shown as a chamber 49 from which the conduit 32 extends and into which a conduit 50, part of the system 24, extends from the intake manifold 5. A valve seat 51 is provided where the conduit 50 enters chamber 49. A valve disc 52 on the armature 53 of the solenoid 46, under spring or gravity force, is biased to close said valve seat 51 when the solenoid is de-energized, thereby closing the conduit 32 and the branch 41 thereof to the vacuum of the intake manifold 5. As a consequence, the spring 27 acts to open the butterfly valve 29, thereby opening the throttle chamber 9 to intake of air from the usual air cleaner connected to the chamber extension 28. Also, the needle valve 39 will be unseated so fuel, under pump pressure, is conducted to the carburetor bowl.

The engine speed-sensing switch 43 may be -governorcontrolled to close when there is a significant rise above idling speed of the engine. The circuit 45 has the switches 43 and 44 in series with the solenoid 46, the battery 47 and the ignition switch 48. As a consequence only when these switches are all closed is the solenoid 46 energized to cause retraction of the armature 53 thereof and opening the conduit system 24 so the vacuum therein may act on the piston 33 and cause closing of the valve 29.

During normal operation of the engine under load, the Switch 43 is closed under control of its governor. However, the throttle stop switch is held open by the foot on the throttle pedal, thereby opening the circuit 45 and causing the solenoid to become de-energized, and shutting off the vacuum to the means 26. Under these conditions, the decelerating valve 29 will be held open by the spring 27, and the fuel from the fuel pump to the carburetor will be flowing past the shut-off valve 36, since vacuum to piston 33 and 40 is shut off by the valve disc 52 engaging seat 51.

When the throttle pedal is released causing the engine to decelerate, the switch 44 automatically closes. The sensing switch 43 will remain closed during engine deceleration so long as the engine speed is of a degree to be appreciably above idling speed. Since both switches 43 and 44 are closed, current will fiow in circuit 45 causing energization of the solenoid 46. As a result, the valve 42 will open allowing vacuum from the intake manifold to act on the pistons 33 and 40, causing the valve 29 to close and shutting off fuel flow to the carburetor. Thus, during this period of deceleration of the engine, no fuel reaches the carburetor and the pressures in the throttle chamber 9 and bowl 11 are equalized. This removal of differential pressures is necessary so fuel will flow from the bowl to the throttle chamber.

When the engine speed lowers to a value approaching idling speed, the switch 43 will open to open circuit 45 and cause the solenoid 46 to de-energize resulting in re-closing of the valve 42 and return of the butterfiy valve 29 to normal open operating position and opening of the shutoff valve 36 to normalize operation of the carburetor. The engine will now idle in the normal way.

If, during deceleration, the throttle is opened, the switch 44 will open and the carburetor automatically returns from its deceleration condition to normal operation under load.

While the foregoing has illustrated and described what is now contemplated to be the best mode of carrying out the invention, the construction is, of course, subject t0 modification without departing from the spirit and scope of the invention. Therefore, it is not desired to restrict the invention to the particular form of construction illustrated and descirbed, but to cover all modifications that may fall within the scope of the appended claims.

Having thus described this invention, what is claimed and desired to be secured by Letters Patent is:

1. In a carburetor for internal combustion engines and having a fuel-feeding system supplied by a fuel pump, idle and off-idle fuel systems, and a throttle chamber and mounted on the intake manifold of such an engine to discharge fuel from the feeding system into the manifold on the side thereof beyond the throttle valve in said throttle chamber, means for shutting off fuel flow to the carburetor during the period that the engine reduces its speed from normal load operation to a level above idle speed, said means comprising:

(a) a shut-off valve in the conduit leading from the fuel pump to the fuel-feeding system,

(b) a decelerating butterfly valve in the throttle chamber on the inlet side thereof and provided with resilient means to maintain the same open during normal operation of the engine under load,

(c) means for moving said deceleration valve to closed position against the bias of said resilient means,

(d) a conduit system connecting the intake manifold to said shut-off valve and deceleration valve moving means,

(e) a normally-closed valve to open said system to conduction of vacuum from the intake mainfold to said shut-off means and deceleration valve means,

(f) an electrical system including in series, a solenoid that, when energized opens the normally closed valve, a normally-closed throttle stop switch that opens when the throttle is operated, and an engine speed-sensing switch controlled by the engine, the latter being normally open and closing as the engine speed rises significantly above idling speed of the engine,

(g) said solenoid being energized only when both said switches are closed, to open the valve in the conduit system, thereby simultaneously shutting off fuel supply to the carburetor and closing the deceleration valve.

2. In a carburetor according to claim 1 in which a passage system interconnects the fuel'feeding system and the throttle chamber to equalize the pressures therein during engine deceleration.

3. In a carburetor according to claim 1 in which the shut-off valve comprises a needle valve, the stem of which is provided with an enlarged piston, the face of said piston being directed toward the stem, and a body in which the stern and the piston are slidingly fitted, a passage in said body opening on said piston face and connected to the conduit system for shutting off the valve by the vacuum in said conduit sytem.

4. In a carburetor according to claim 1 in which the deceleration valve moving means comprises a vented y5 cylinder connected to the conduit system, a piston fitted in said cylinder and facing said connection, a connection between the piston and the deceleration valve, the vacuum in said system being elfective to move the piston in a direction to cause said valve to move from open to closed position.

5. In a carburetor according to claim 2 in which the deceleration valve is fitted to the throttle chamber to close the same when moved to closed position and the throttle valve tting the throttle chamber with such clearance, when in closed position, as to provide pressure equalizing communication between the intake manfold and the throttle chamber.

5/1933 ll/l938 2/1946 6/1966 3/1968 Mallory. Winfield. Mallory. Walker. Walker.

U.S. Cl. X.R. 

